1. Field of the Invention
The present invention relates to an animate body detector and, more specifically, to an animate body detector for determining whether a subject to be checked is an animate body.
2. Description of Related Art
Technologies on security of information processing systems are developing with the progression of computerization society. For example, it has been conventional to use ID cards to control entry to a computer room, but they tend to be lost or stolen. For this reason, ID cards are being replaced by an individual validation system which checks individuals to enter the room by consulting individuals' fingerprints or the like previously registered.
In such an individual validation system, a check is sometimes passed by creating a replica of a registered fingerprint. Accordingly, an individual validation system must determine whether subjects to be checked are animate bodies, besides making fingerprint comparisons.
The technique for determining whether subjects to be checked are animate bodies is disclosed in Japanese Patent Laid-Open No. Hei 3-38621 that detects animate bodies by animate body detection means exploiting skin pressure dependence.
General animate body detectors exploiting capacitance detect an animate body by using a sine wave voltage to measure the capacitance of a contacting subject to be checked.
However, the above-mentioned prior art has a problem that many parts including a light source are required and circuit configuration is complicated because an animate body is detected in a way that irradiates light to a subject to be checked and measures the reflection factor of its reflected light.
The prior art of using capacitance described later also has a problem that it is difficult to miniaturize an animate body detector because a sine wave voltage generator is required to measure capacitance.